>> Proposal number two: don't make any changes to the syntax, but treat these as *literally* numeric scale factors.
>> k = kilo = 10**3
>> M = mega = 10**6
>> G = giga = 10**9
>> int_value = 8*M float_value = 8.0*M
>> fraction_value = Fraction(1, 8)*M
>> decimal_value = Decimal("1.2345")*M

This is the only variant I've seen that I would consider "not awful." Of course, this involves no change in the language, but just a module on PyPI.

Of the awful options, a suffix underscore and multiplier (1.1_G) is the least awful. It's a little bit reminiscent of the optional internal underscores being added to literals.